1. Field of the Invention
The present invention is directed to film processing, and more specifically, to devices and methods for high speed microfiche duplication in which a master film and a copy film are brough together and light is passed through the master film to expose the copy film.
2. Description of the Prior Art
The storage of information on microfiche is a particularly popular practice. Typically, a film of microfiche has a plurality of microfiche frames arragned thereon, one or more frames acrosss the width of the film and many frames along the length of the film, i.e., as a column or columns. The film is generally stored by winding film around a cylindrical surface, e.g., a spool, to form a roll of film.
The need to copy microfiche film frequently arises. For many years, the designs of microfiche copiers have been changed in attempts to increase the rate at which fiche are copied, to improve copy quality and to reduce man-power demands. It is not uncommon for installationsto have as many as 50 or more machines being operated simultaneously by 20 or more persons, each machine copying fiche at a maximum rate of about 1000 fiche/hour.
There are three primary types of film used for copying from a master film of microfiche, namely, silver film, diazo film and vesicular film. Diazo film is currently used as the copy film for more than a majority of microfiche copying. Silver film is muchmore expensive (about four times) than diazo film, and vesicular film, which is exposed by being subjected to ultraviolet light and heat, does not have a dark background, which is frequently desirable. Diazo film is exposed by being subjected to ultraviolet light and produces copies having dark backgrounds. When copying onto diazo film, it is not necessary that the film be heated and a dark room is not necessary.
Considerable research and development has been conducted in attempts to develop a machine which provides more rapid duplication of microfiche, without sacrificing the quality of the copies made. There is a continuing need for improved microfiche copiers which are capable of rapidly producing copies of microfiche having good quality and which do not require extensive surveillance or complex manual adjustment by operators.
SUMMARY OF THE INVENTION
The present invention is directed to devices and method for making good quality copies of microfiche at rapid rates of reproduction. The present invention is also directed to providing such a machine which is relatively simple to operate. A device in accordance with the present invention comprises:
a master payout station from which master film is supplied;
a copy payout station from which copy film is supplied to form a master film-copy laminate;
an exposure station comprising an ultraviolet ray source and an exposure surface over which the master film and the copy film pass, such that ultraviolet light from the ultraviolet ray source passes through the exposure surface and the master film and then exposes the copy film;
a plurality of belt rollers positioned about the exposure station, each belt roller having a belt surface;
an endless rensioning belt threaded around the rollers and in contact with the belt surfaces of the rollers, the tensioning belt pressing the master film and the copy film into initmate contact with each other and with the exposure surface;
a master take-up station at which the master film is collected after passing over the exposure surface;
a development section for developing the copy film after the copy film has been exposed;
a cooling section for cooling the developed copy film;
a copy take-up station at which the copy film is collected after passing through the cooling section; and
means for driving the copy film through the exposure station, the development section and the cooling section.
In accordance with a preferred aspect of the present invention, the master film and the tensioning belt are passively driven by the drive means by virtue of contact between the copy film and each of the master film and the tensioning belt. The exposure surface is rotated by virtue of contact with the master film.
In another preferred aspect of the invention, each of the belt rollers comprises a cylinder having a surface and two circular ends, each roller being rotatable about an axis of rotation through the centers of the ends, each of the surfaces having two helical grooves formed therein, such that as the tensioning belt passes over each surface, the grooves converge or diverge as the roller rotates, i.e., the grooves tend to cause the belt to laterally expand or contract. Each of the belt rollers preferably further comprises a crown formed as a ring on the surface of the roller concentric with the axis of rotation and located between the grooves. The belt rollers are preferably arranged such that the tensioning belt contacts converging and diverging grooves alternatingly on successive surfaces of the belt rollers.
The means for driving the copy film preferably comprises a first drive means positioned between the exposure station and the development section and a second drive means positioned such that the copy film contacts the second drive means just prior to being collected at the copy take-up station.
In another preferred aspect of the invention, the cooling section comprises (1) an air knives section comprising air knife units having slots formed therein through which pressurized, filtered air is passed to contact the copy film and (2) a rotatable, cylindrical chill drum, around which the copy film passes, the chill drum having a plurality of cylindrical holes formed therethrough, through which cooling air is blown.
According to another preferred aspect of the present invention, the development section comprises a main developer chamber and means for supplying ammonia vapors to the main developer chamber, the main developer chamber having an inlet and an outlet through which the copy film passes, the main developer chamber inlet and outlet each comprising seals, the seals each comprising closely packed elongate fibers formed of a hybrid of ataprine and a neoprine which inhibit flow of ammonia vapors through the main developer chamber inlet and outlet.
In a modification in accordance with the present invention, the master film is formed as an endless loop. In accordacne with this aspect, the master film, in a laminate with the copy film, pases through the exposure station, into a loop rack, and back through the exposure station. Accordingly, the master film is not collected at the master take-up station until the desired number of copies of the master film have been made.
The present invention is also directed to a method for copying images on a master microfiche film onto a copy microfiche film. The method comprises:
unwinding master film from a master payout station and copy film from a copy payout station by operating drive means, which engage the copy film;
bringing the master film and the copy film together to form a master film-copy film laminate;
passing the master film-copy film laminate over an exposure surface;
directing ultraviolet rays through the exposure surface and the master film to the copy film, thereby exposing the copy film;
directing an endless tensioning belt around a plurality of belt rollers having belt-contacting surfaces and being positioned such that the tensioning belt presses the copy film against the master film, which is pressed against the exposure surface, thereby holding the copy film in pressing, substantially non-slipping contact with the master film and holding the master film in pressing, substantially non-slipping contact with the exposure surface such that the master film and the tensioning belt are passively driven by the drive means by virtue of contact between the copy film and each of the master film and the tensioning belt, and the exposure surfaces is roatated by virtue of contact with the master film;
collecting the master film at a master take-up station after the master film has passed over the exposure surface;
developing the exposed copy film;
cooling the developed copy film; and
collecting the cooled copy film at a copy take-up station.
In a preferred aspect in accordance with the method of the present invention, the tensioning belt is laterally expanded and contracted as it passes around the belt rollers, which have helical grooves formed in the belt-contacting surfaces thereof, the grooves being formed such that upon rotation of each roller while in contact with the tensioning belt, the grooves converge or diverge relative to the tensioning belt to laterally contract or expand the tensioning belt. Preferably, the tensioning belt is laterally contracted and expanded alternatingly by contacting belt roller surfaces having grooves which converge and diverge on successive rollers.